RealGM Analysis

There has been a lot of discussion of what happened when the NCAA changed its foul enforcement rules in 2013-14. Three trends seemed clear. Points per possession were higher, free throw attempts were up, and turnovers were down. But I have not seen any discussion about how this impacted different types of players.

Let me classify players into five groups. First, I break out all big men, essentially all players over 6’8” tall. For teams that do not have at least three rotation players 6’8” or taller, I will also classify some shorter players as forwards, based on stats such as rebounding.

I next break out the point guards based on Verbal Commits recruiting classifications. Then I adjust based on a few measured stats. If a guard has an assist rate over 20%, I reclassify him as a PG, even if he was a SG out of high school. If a guard has an assist rate under 8%, I remove him from the PG group, even if he was classified as a PG out of high school.

That leaves me with a large group of off-guards and wings. I classify these players into three groups based on how often they shoot threes. For players that take over 66% of their shots from three point range, I classify them as three point specialists. For players that take under 33% of their shots from three point range, I classify them as non-shooters. (These are your typical wing players.) The remaining players that take 33-66% of their shots from three point range are your typical perimeter players that can drive and shoot.

Obviously not every player fits into one category, but for now this is how I grouped the various types of players. I am going to look at all D1 players who played at least 30% of their teams minutes in 2012-13 (before the rule change) and 2013-14 (after the rule change).

Number of Observations

2012-13

2013-14

Point Guard

634

639

Three Point Specialists

143

133

Drive and Shoot

514

522

Non-Shooters

315

316

Big Men

974

981

The next table shows that not every position on the floor is equally efficient. Three point specialists are typically the most efficient, but that is partly because they shoot less. On average, three point specialists use only 16% of the possessions when on the floor. All the other position types average 20-21% of the possessions used when on the floor.

The non-shooters tend to have some of the lowest efficiency ratings, but keep in mind that I have broken out this group based on their tendency not to shoot threes, so it isn’t a surprise that they are less efficient. The more interesting fact is that PGs tend to be a little bit less efficient. Part of this may be the fact that teams feel obligated to have a PG on the floor at all times, even if he is less talented. A team can get by without a true SG (see North Carolina last year), but no team can really run its offense without a true PG. And thus you get some less effective PGs who play major minutes.

Another thing to keep in mind is that ORtg isn’t a perfect measure of player value. When Dean Oliver developed the metric, he wanted to assign some credit for made shots to the assisting player and players that got offensive rebounds that led to the basket. But even though he had a strong basis for his formula, nothing says that his weight for assists is accurate for every team in every situation. If a PG drives into the lane and collapses a defense, and there are two passes for the wide open shot, he might not get any credit for creating the opportunity. Some PGs are more valuable than the measured stats indicate, and some PGs are less valuable.

Moreover, non-shooters at the wing position are typically some of the better defensive players. These are typically tall athletic players who help stop opposing scorers. Thus just because PGs and non-shooters are showing up as less efficient here, doesn’t mean that teams are making a mistake by putting these players on the floor.

ORtg in 2013-14

10th percentile

Median

90th percentile

Point Guard

88

103

116

Three Point Specialists

97

110

126

Drive and Shoot

93

106

119

Non-Shooters

87

101

113

Big Men

93

106

119

Next, I want to look at how each type of player was impacted by the rule changes. My expectation was that the impact of the new foul rules would not be uniform. For example, I would expect a rule limiting hand-checks or impacting block/charge calls to benefit PGs more than three point specialists.

On the other hand, there tends to be a bit of an equilibrium situation in team defense. Even if a rule change has a smaller direct impact on a three point specialist, when devising a game plan, teams still have to weigh costs and benefits. And if an opposing PG is now more dangerous because of the new block/charge and hand-checking rules, that might result in the best defender spending less time on a good three point shooter and more time on the PG. That might still benefit the SG indirectly.

Regardless of whether the effects are direct or indirect, here is how the ORtgs changed for these groups from 2012-13 to 2013-14.

Difference in ORtg

10th percentile

Median

90th percentile

Point Guard

+3

+4

+3

Three Point Specialists

+6

+3

+5

Drive and Shoot

+5

+4

+4

Non-Shooters

+5

+4

+3

Big Men

+5

+3

+4

The overall trend shouldn’t be a surprise given the higher points per possession across D1. If you run a t-test, the difference in the means of the two distributions is statistically significantly different, meaning that on average players were clearly more efficient in 2013-14, after the rule changes.

But I was shocked to see that the rule changes tended to impact all positions fairly equivalently. Spot up shooters gained just as much as big men and point guards.

There seems to be some evidence that the new rules helped bad players more, as the 10th percentile generally shows a larger improvement. Turnover prone players tend to have the worse efficiency ratings, and the worst players had fewer turnovers last season. But for the most part, the new rules benefited players with all sorts of variation in skills.

But even if the raw ORtg changes were equivalent, the changes in foul calls and turnovers were not identical. Next week I will discuss how different types of players benefited in different ways from the rule changes last year.